Organic light-emitting display apparatus

ABSTRACT

An organic light-emitting display apparatus includes a pixel electrode, a light emission layer over the pixel electrode, an opposite electrode covering the light emission layer, a plurality of upper layers over the opposite electrode, a light-shielding layer over the upper layers. A distance L between an edge of an emission area of the light emission layer and an edge of the light-shielding layer when viewed in a thickness direction satisfies Inequality below: 
     
       
         
           
             
               
                 
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             wherein m represents the number of the upper layers, n i  and d i  represent a refraction index and a thickness of each of the upper layers, respectively, d BM  represents a thickness of the light-shielding layer, n CF  represents a refraction index of the color filter layer, n air  represents a refraction index of air, and θ air  represents a refraction angle in external air after light generated from the light emission layer passes through the color filter layer.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. patent application Ser. No.15/147,758, filed May 5, 2016, which claims priority under 35 U.S.C. §119 of Korean Patent Application No. 10-2015-0138613, filed on Oct. 1,2015, in the Korean Intellectual Property Office, the disclosures ofwhich are incorporated by reference herein in their entireties.

BACKGROUND 1. Field

One or more embodiments relate to an organic light-emitting displayapparatus, and more particularly, to an organic light-emitting displayapparatus with improved extraction efficiency of light.

2. Discussion of the Related Technology

In a general top-emission type organic light-emitting display apparatus,light emitted from an emission layer passes through a cathode, layersabove the cathode, and is emitted externally. As the light emitted fromthe light emission layer passes through various layers, refraction oflight may occur at interfaces and an optical path is determinedaccordingly.

SUMMARY

However, from among light emitted from an emission layer of a typicalorganic light-emitting display apparatus, a large proportion of light isnot externally emitted. This leads to brightness reduction, and thusincreases power consumption to increase brightness.

Thus, one or more embodiments are directed to an organic light-emittingdisplay apparatus with improved extraction efficiency of light.

Additional aspects will be set forth in part in the description whichfollows and, in part, will be apparent from the description, or may belearned by practice of the presented embodiments.

One aspect of the invention provides an organic light-emitting displayapparatus, which may comprise: a pixel electrode disposed over asubstrate; a light emission layer disposed over the pixel electrode; anopposite electrode covering the light emission layer; a plurality ofupper layers disposed over the opposite electrode, wherein the number ofthe plurality of upper layers is m which represents a natural numbergreater than one; a light-shielding layer disposed over the plurality ofupper layers, the light-shielding layer not overlapping the lightemission layer; and a color filter layer disposed over the upper layers,wherein L is defined by a distance between an edge of an emission areaof the light emission layer and an edge of the light-shielding layerwhen viewed in a viewing direction perpendicular to a major surface ofthe substrate, wherein the distance L satisfies Inequality below:

$\begin{matrix}{L \geq {{\sum\limits_{i = 1}^{m}{d_{i}{\tan\left( {\sin^{- 1}\left( {\frac{n_{air}}{n_{i}}\sin\;\theta_{air}} \right)} \right)}}} + {d_{BM}{\tan\left( {\sin^{- 1}\left( {\frac{n_{air}}{n_{CF}}\sin\;\theta_{air}} \right)} \right)}}}} & \lbrack{Inequality}\rbrack\end{matrix}$wherein n_(i) represents a refraction index of each of the upper layers,d_(i) represents a thickness of each of the upper layers, d_(BM)represents a thickness of the light-shielding layer, n_(CF) represents arefraction index of the color filter layer, n_(air) represents arefraction index of air, and θ_(air) represents a refraction angle inexternal air after light generated from the light emission layer passesthrough the color filter layer.

In the foregoing apparatus, the display apparatus may further comprise apixel-defining layer covering a boundary of the pixel electrode suchthat a central area of the pixel electrode is exposed through a holedefined by the pixel-defining layer. The emission area of the lightemission layer may correspond to an area of the pixel electrode, whichis not covered by the pixel-defining layer. The edge of the emissionarea of the light emission layer may correspond to a boundary of thearea of the pixel electrode, which is not covered by the pixel-defininglayer. The display apparatus may further comprise a pixel-defining layerdisposed over the substrate and defining a hole that allows a portion ofthe light emission layer not to overlap the pixel-defining layer whenviewed in the viewing direction, wherein the emission area is defined bythe non-overlapping portion of the light emission layer.

Still in the foregoing apparatus, a lowermost layer among the pluralityof upper layers may directly contact the opposite electrode. A bottomsurface of the color filter layer facing the light emission layer and abottom surface of the light-shielding layer facing the light emissionlayer may be on the same plane. A thickness of the color filter layermay be substantially equal to or substantially greater than a thicknessof the light-shielding layer. θ_(air) may be 90°. The plurality of upperlayers may comprise a first inorganic encapsulating layer, an organicencapsulating layer on the first inorganic encapsulating layer, and asecond inorganic encapsulating layer on the organic encapsulating layer.Each of the first inorganic encapsulating layer and the second inorganicencapsulating layer may comprise at least one selected from siliconoxide, silicon nitride, and silicon oxynitride, and the organicencapsulating layer may comprise at least one selected frompolyacrylate, polyethylene terephthalate, polyethylene naphthalate,polycarbonate, polyimide, polyethylene sulfonate, polyoxymethylene, andpolyarylate. The organic encapsulating layer may be disposed between anddirectly contact both the first and second inorganic encapsulatinglayers.

Yet in the foregoing apparatus, the plurality of upper layers maycomprise a plurality of inorganic encapsulating layers and a pluralityof organic encapsulating layers which are alternatively stacked on oneanother. Each of the inorganic encapsulating layers may comprise atleast one selected from silicon oxide, silicon nitride, and siliconoxynitride, and each of the organic encapsulating layers may comprise atleast one selected from polyacrylate, polyethylene terephthalate,polyethylene naphthalate, polycarbonate, polyimide, polyethylenesulfonate, polyoxymethylene, and polyarylate.

The edge of the light-shielding layer may define an opening throughwhich light emitted from the light emission layer toward the upperlayers travels, wherein the edge of the light-shielding layer forms aclosed loop surrounding the emission area of the light emission layerwhen viewed in the viewing direction. The edge of the light-shieldinglayer may define an opening, wherein the distance L is defined tosatisfy said Inequality such that substantially the entire portion oflight emitted from the light emission layer toward the upper layerstravels through the opening. The edge of the light-shielding layer mayface the edge of the emission area of the light emission layer whenviewed in the viewing direction.

Another aspect of the invention provides an organic light-emittingdisplay apparatus, which may comprise: an array of pixels disposed overa substrate, each pixel comprising a first sub-pixel comprising a firstlight emission layer configured to emit first light having a firstwavelength within a first wavelength range, a second sub-pixelcomprising a second light emission layer configured to emit second lighthaving a second wavelength within a second wavelength range, the secondwavelength of the second light being longer than a wavelength of lightwithin the first wavelength range, and a third sub-pixel comprising athird light emission layer configured to emit third light having a thirdwavelength within a third wavelength range, the third wavelength of thethird light being longer than a wavelength of light within the secondwavelength range; an encapsulating layer disposed over the first tothird sub-pixels; a light-shielding layer disposed over theencapsulating layer; and a color filter layer disposed on theencapsulating layer, wherein L1<L2<L3 is satisfied when L1 represents adistance between an edge of an emission area of the first light emissionlayer and a first edge of the light-shielding layer when viewed in aviewing direction perpendicular to a major surface of the substrate, L2represents a distance between an edge of an emission area of the secondlight emission layer and a second edge of the light-shielding layer whenviewed in the viewing direction, and L3 represents a distance between anedge of an emission area of the third light emission layer and a thirdedge of the light-shielding layer when viewed in the viewing direction.

In the foregoing apparatus, the first edge of the light-shielding layermay define an opening through which light emitted from the first lightemission layer travels, wherein the distance L1 is determined such thatsubstantially the entire amount of the light emitted from the firstlight emission layer toward the encapsulation layer travels through theopening. The first edge may form a first closed loop surrounding theemission area of the first light emission layer, wherein the second edgemay form a second closed loop surrounding the emission area of thesecond light emission layer, wherein the third edge may form a thirdclosed loop surrounding the emission area of the third light emissionlayer.

According to one or more embodiments, an organic light-emitting displayapparatus includes a pixel electrode, an emission layer over the pixelelectrode, an opposite electrode covering the emission layer, m numberof upper layers over the opposite electrode, a light-shielding layerover the upper layers, the light-shielding layer not overlapping theemission layer, and a color filter layer over the upper layers. Adistance L between an edge of an emission area of the emission layertoward the light-shielding layer and an edge of the light-shieldinglayer toward the emission layer satisfies Inequality below:

$\begin{matrix}{L \geq {{\sum\limits_{i = 1}^{m}{d_{i}\tan\left( {\sin^{- 1}\left( {\frac{n_{air}}{n_{i}}\sin\;\theta_{air}} \right)} \right)}} + {d_{BM}{\tan\left( {\sin^{- 1}\left( {\frac{n_{air}}{n_{CF}}\sin\;\theta_{air}} \right)} \right)}}}} & \lbrack{Inequality}\rbrack\end{matrix}$

wherein n_(i) represents a refraction index of each of the upper layers,d_(i) represents a thickness of each of the upper layers, d_(BM)represents a thickness of the light-shielding layer, n_(CF) represents arefraction index of the color filter layer, n_(air) represents arefraction index of air, and θ_(air) represents a refraction angle inexternal air after light generated from the emission layer passesthrough the color filter layer.

The organic light-emitting display apparatus may further include apixel-defining layer covering a boundary of the pixel electrode suchthat a central area of the pixel electrode is exposed, and the upperlayers may correspond to the pixel electrode and the pixel-defininglayer.

The emission area of the emission layer may correspond to an area of thepixel electrode, which is not covered by the pixel-defining layer. Theedge of the emission area of the emission layer toward thelight-shielding layer may correspond to a boundary of the area of thepixel electrode, which is not covered by the pixel-defining layer.

A lowermost layer toward the emission layer, from among the m number ofupper layers, may directly contact the opposite electrode.

A bottom surface of the color filter layer toward the emission layer anda bottom surface of the light-shielding layer toward the emission layermay be on a same plane. A thickness of the color filter layer may beequal to or greater than a thickness of the light-shielding layer.

θ_(air) may be 90°.

The m number of upper layers may include a first inorganic encapsulatinglayer, an organic encapsulating layer on the first inorganicencapsulating layer, and a second inorganic encapsulating layer on theorganic encapsulating layer. Each of the first inorganic encapsulatinglayer and the second inorganic encapsulating layer may include at leastone selected from silicon oxide, silicon nitride, and siliconoxynitride. The organic encapsulating layer may include at least oneselected from polyacrylate, polyethylene terephthalate, polyethylenenaphthalate, polycarbonate, polyimide, polyethylene sulfonate,polyoxymethylene, and polyarylate.

The m number of upper layers may include a plurality of inorganicencapsulating layers and a plurality of organic encapsulating layerswhich are alternatively stacked on one another. Each of the inorganicencapsulating layers may include at least one selected from siliconoxide, silicon nitride, and silicon oxynitride. Each of the organicencapsulating layers may include at least one selected frompolyacrylate, polyethylene terephthalate, polyethylene naphthalate,polycarbonate, polyimide, polyethylene sulfonate, polyoxymethylene, andpolyarylate.

According to one or more embodiments, an organic light-emitting displayapparatus includes a first sub-pixel comprising a first emission layeremitting first light having wavelength belonging to a first wavelengthband, a second sub-pixel comprising a second emission layer emittingsecond light having wavelength belonging to a second wavelength band,the wavelength of the second light being longer than wavelength of lightbelong to the first wavelength band, a third sub-pixel comprising athird emission layer emitting third light having wavelength belonging toa third wavelength band, the wavelength of the third light being longerthan wavelength of light belonging to the second wavelength band, anencapsulating layer over the first to third sub-pixels, alight-shielding layer over the encapsulating layer and corresponding toareas between the first to third sub-pixels, and a color filter layer onthe encapsulating layer. L1<L2<L3 is satisfied when L1 represents adistance between an edge of an emission area of the first emission layertoward the light-shielding layer and an edge of the light-shieldinglayer toward the first emission layer, L2 represents a distance betweenan edge of an emission area of the second emission layer toward thelight-shielding layer and an edge of the light-shielding layer towardthe second emission layer, and L3 represents a distance between an edgeof an emission area of the third emission layer toward thelight-shielding layer and an edge of the light-shielding layer towardthe third emission layer.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects will become apparent and more readilyappreciated from the following description of the embodiments, taken inconjunction with the accompanying drawings in which:

FIG. 1 is a cross-sectional view schematically illustrating a portion ofan organic light-emitting display apparatus according to an embodimentand FIG. 7 is a cross-sectional view schematically illustrating multiplesub-pixels of one pixel of the organic light-emitting display apparatusof FIG. 1;

FIG. 2 is a conceptual view schematically illustrating an optical pathin the portion of the organic light-emitting display apparatus of FIG.1;

FIG. 3 is a graph of a refraction index according to wavelengths ofsilicon oxide;

FIG. 4 is a graph of a refraction index according to wavelengths ofsilicon nitride;

FIG. 5 is a graph of a refraction index according to wavelengths ofpolyacrylate; and

FIG. 6 is a graph of a refraction index according to wavelengths ofpolyethylene terephthalate.

DETAILED DESCRIPTION

As the inventive concept allows for various changes and numerousembodiments, particular embodiments will be illustrated in the drawingsand described in the written description. The effect and features of theinventive concept and the method of realizing the effect and thefeatures will be clear with reference to the embodiments described belowwith reference to the drawings. However, the inventive concept may beembodied in various forms and should not be construed as being limitedto the embodiments. As used herein, the term “and/or” includes any andall combinations of one or more of the associated listed items.Expressions such as “at least one of,” when preceding a list ofelements, modify the entire list of elements and do not modify theindividual elements of the list.

Hereinafter, the embodiments will be described with reference to thedrawings. Like reference numerals refer to like elements in thedrawings, and thus, descriptions of similar or identical elements willnot be repeated.

It will be understood that when a layer, region, or component isreferred to as being formed or disposed “on,” another layer, region, orcomponent, it can be formed or disposed directly on and contact theother layer, region, or component, or it can be formed or disposedindirectly on the other layer, region or component such that one or moreintervening layers, regions or components may be present therebetween.

Sizes of elements in the drawings may be exaggerated for convenience ofexplanation. In other words, since sizes and thicknesses of componentsin the drawings are arbitrarily illustrated for convenience ofexplanation, the following embodiments are not limited thereto.

In the following examples, the x-axis, the y-axis and the z-axis are notlimited to three axes of a rectangular coordinate system, and may beinterpreted in a broader sense. For example, the x-axis, the y-axis, andthe z-axis may be perpendicular to one another, or may representdifferent directions that are not perpendicular to one another.

FIG. 1 is a cross-sectional view schematically illustrating a portion ofan organic light-emitting display apparatus according to an embodiment;

The organic light-emitting display apparatus according to the presentembodiment includes a pixel electrode 210, an emission layer 220 overthe pixel electrode 210, four upper layers, namely, an oppositeelectrode 230, a first inorganic encapsulating layer 310, an organicencapsulating layer 320, and a second inorganic encapsulating layer 330over the light emission layer 220, a light-shielding layer 410 over theupper layers 230, 310, 320, and 330, and a color filter layer 420 overthe upper layers 230, 310, 320, and 330.

When necessary, as shown in FIG. 1, a thin film transistor TFT or acapacitor Cap may be provided on a substrate 100, and the pixelelectrode 210 may be electrically connected to the thin film transistorTFT. The substrate 100 may include various materials, for example, aglass material, a metallic material, or a plastic material such aspolyethylene terephthalate (PET), polyethylene naphthalate (PEN), andpolyimide. Also, a buffer layer 110, a gate insulating layer 130, aninterlayer insulating layer 150, and a planarization layer 170 may beprovided on the substrate 100. The buffer layer 110 may preventimpurities from penetrating into a semiconductor layer of the thin filmtransistor TFT. The gate insulating layer 130 may insulate thesemiconductor layer of the thin film transistor TFT from a gateelectrode. The interlayer insulating layer 150 may insulate asource/drain electrode and the gate electrode of the thin filmtransistor TFT from each other. The planarization layer 170 may coverthe thin film transistor TFT and have a substantially flat top surface.

The pixel electrode 210 may be a (semi) transparent electrode or areflection electrode. When the pixel electrode 210 is a (semi)transparent electrode, the pixel electrode 210 may include, for example,indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide ZnO), indiumoxide (In₂O₃), indium gallium oxide (IGO), or aluminum zinc oxide (AZO).When the pixel electrode 210 is a reflection electrode, the pixelelectrode 210 may include a reflection layer including silver (Ag),magnesium (Mg), aluminum (Al), platinum (Pt), palladium (Pd), gold (Au),nickel (Ni), neodymium (Nd), iridium (Ir), chrome (Cr), or a compoundthereof, and a layer including ITO, IZO, ZnO, or In₂O₃. However,composition and materials of the pixel electrode 210 are not limited tothe above and various modifications may be adapted.

In order to define a location of the light emission layer 220 amonglayers above the pixel electrode 210, a pixel-defining layer 180 may beprovided as shown in FIG. 1. The pixel-defining layer 180 may cover aboundary of the pixel electrode 210 such that a central area of thepixel electrode 210 is exposed. Accordingly, the pixel-defining layer180 may define a pixel. Also, the pixel-defining layer 180 may increasea distance between an edge of the pixel electrode 210 and the oppositeelectrode 230 above the pixel electrode 210 so as to prevent an arc atthe edge of the pixel electrode 210.

The light emission layer 220 is located on the pixel electrode 210. Anintermediate layer may be provided between the pixel electrode 210 andthe light emission layer 220. For example, a hole injection layer and/ora hole transport layer may be provided on the pixel electrode 210, andthe light emission layer 220 may be provided on the hole injection layerand/or the hole transport layer.

As shown in FIG. 1, the opposite electrode 230 is located on the lightemission layer 220. The opposite electrode 230 may be integrally formedas one body so that one opposite electrode 230 may correspond to aplurality of pixels. Therefore, the opposite electrode 230 maycorrespond to not only the light emission layer 220 but also topsurfaces of the pixel-defining layer 180. The opposite electrode 230 maybe a (semi) transparent electrode. Accordingly, the opposite electrode230 may include a layer including lithium (Li), calcium (Ca), LiF/Ca,LiF/Al, Al, Mg, or a compound thereof, and a layer including a (semi)transparent material such as ITO, IZO, ZnO, or In₂O₃.

The pixel electrode 210, the light emission layer 220, and the oppositeelectrode 230 may be regarded as an organic light-emitting device (OLED)200. The OLED 200 may emit light having brightness that is determinedaccording to an electric signal applied to the pixel electrode 210 viathe thin film transistor TFT.

An encapsulation layer 300 is provided on the OLED 200. Theencapsulation layer 300 may not only correspond to the light emissionlayer 220 but also the top surfaces of the pixel-defining layer 180. Theencapsulation layer 300 may have a multi-layer structure. For example,the encapsulation layer 300 may include the first inorganicencapsulating layer 310, the organic encapsulating layer 320, and thesecond inorganic encapsulating layer 330, as shown in FIG. 1. Theencapsulation layer 300 may protect the OLED 200 from externalimpurities such as oxygen or moisture.

The first inorganic encapsulating layer 310 or the second inorganicencapsulating layer 330 may include various materials, for example,silicon nitride, silicon oxide, and/or silicon oxynitride, or metaloxide, metal nitride, metal oxynitride, or metal carbide. The organicencapsulating layer 320 between the first and second inorganicencapsulating layers 310 and 330 may planarize curves of the firstinorganic encapsulating layer 310. Also, since organic encapsulatinglayer 320 covers the first inorganic encapsulating layer 310, even whenthere is a crack in the first inorganic encapsulating layer 310, thecrack may not extend further into the second inorganic encapsulatinglayer 330. The organic encapsulating layer 320 may include at least oneselected from the group consisting of polyacrylate, PET, PEN,polycarbonate, polyimide, polyethylene sulfonate, polyoxymethylene, andpolyarylate.

The light-shielding layer 410 and the color filter layer 420 areprovided on the encapsulation layer 300. The light-shielding layer 410is provided on the encapsulation layer 300 without overlapping the lightemission layer 220, and the color filter layer 420 is provided on theencapsulation layer 300 and overlaps the light emission layer 220. Sincethe light-shielding layer 410 does not overlap the light emission layer220, the light-shielding layer 410 may be regarded as being locatedcorrespondingly to areas between pixels. For example, when viewing theorganic light-emitting display apparatus on z-axis that is perpendicularto an xy-plane and extends in a direction of perpendicular to a majorsurface of the substrate 100 or a thickness direction of the displayapparatus, the light-shielding layer 410 may surround each of thepixels. The light-shielding layer 410 may be regarded as surrounding anemission area of the light emission layer 220.

The light-shielding layer 410 may prevent external light reflection andincrease contrast of the organic light-emitting display apparatus. Thelight-shielding layer 410 may include a material such as Cr, Al, silicon(Si), or an oxide thereof. The color filter layer 420 may restrict awavelength of light to be emitted externally, from among light generatedby the light emission layer 220, within a predetermined wavelength band,or may prevent a portion of external light, which is incident on thecolor filter layer 420 and does not belong to the predeterminedwavelength band, from being reflected externally.

Since the light-shielding layer 410 and the color filter layer 420 arelocated on the encapsulation layer 300, a bottom surface of thelight-shielding layer 410 facing the light emission layer 220 (−zdirection) and a bottom surface of the color filter layer 420 facing thelight emission layer 220 (−z direction) may be on the same plane. Inthis case, the color filter layer 420 may be thicker than thelight-shielding layer 410, as shown in FIG. 1, and thus, the colorfilter layer 420 may cover the an upper surface of the light-shieldinglayer 410. However, the embodiments are not limited thereto, and thecolor filter layer 420 may be as thick as the light-shielding layer 410.

The organic light-emitting display apparatus according to the presentembodiment may further include a window 500. The window 500 is atransparent layer and be located at an outermost area of the organiclight-emitting display apparatus.

Hereinafter, an optical path in the organic light-emitting displayapparatus according to the present embodiment will be described.

FIG. 2 is a conceptual view schematically illustrating an optical pathin the portion of the organic light-emitting display apparatus ofFIG. 1. FIG. 2 shows a sectional view taken along a plane which isperpendicular to a major surface of a substrate of the displayapparatus. Although FIG. 2 shows that the organic light-emitting displayapparatus according to the present embodiment does not satisfy thecondition of Inequality 9 shown below, this is only for convenience ofdescription and illustration. As shown in FIG. 2, light emitted by thelight emission layer 220 passes through the opposite electrode 230, theencapsulation layer 300, the color filter layer 420, and the window 500and is emitted externally. In this case, refraction occurs at interfacesbased on Snell's law.

In this case, the opposite electrode 230 may have a thickness of onlyfew nm (nanometer) to tens of nm, whereas the encapsulation layer 300and the light-shielding layer 410 may be much thicker than the oppositeelectrode 230, e.g., about few μm. An electron transport layer and/or anelectron injection layer may be provided between the light emissionlayer 220 and the opposite electrode 230. However, the light emissionlayer 220, the electron transport layer, and the electron injectionlayer may have a thickness of only few nm to tens of nm.

Hereinafter, with regard to an optical path, by which light generated bythe light emission layer 220 travels before being externally emitted, adisplacement in a direction (+x direction) perpendicular to a forwarddirection (+z direction) that is perpendicular to the pixel electrode210 will be described. Since the light emission layer 220, the electrontransport layer, and the electron injection layer have a thickness ofonly few nm to tens of nm, when describing the displacement in thedirection (+x direction) in which light generated by the light emissionlayer 220 travels until being externally emitted, it is acceptable toonly consider a displacement in the encapsulation layer 300 anddisregard a displacement in the electron transport layer and/or theelectron injection layer, or the opposite electrode 230.

A refraction index of the first inorganic encapsulating layer 310 may beindicated by ‘n₁,’ a refraction index of the organic encapsulating layer320 may be indicated by ‘n₂,’ a refraction index of the second inorganicencapsulating layer 330 may be indicated by ‘n₃,’ a refraction index ofthe color filter layer 420 may be indicated by ‘n_(CF),’ a refractionindex of the window 500 may be indicated by ‘n_(w).’ Light incidentangle at an interface between the first inorganic encapsulating layer310 and the organic encapsulating layer 320 is indicated by ‘θ₁,’ alight refraction angle at the interface is indicated by ‘θ₂,’ a lightrefraction angle at an interface between the organic encapsulating layer320 and the second inorganic encapsulating layer 330 is indicated by‘θ₃,’ a light refraction angle at an interface between the secondinorganic encapsulating layer 330 and the color filter layer 420 isindicated by ‘θ_(CF),’ a light refraction angle at an interface betweenthe color filter layer 420 and the window 500 is indicated by ‘θ_(w),’and a light refraction angle at an interface between the window 500 andexternal air is indicated by ‘θ_(air).’ The relationship between theindices and angles at the interfaces may be as defined below in Equation1 based on Snell's law (wherein i is 1 or 2).n _(i) sin θ_(i) =n _(i+1) sin θ_(i+1) , n ₃ sin θ₃ =n _(CF) sin θ_(CF)n _(CF) sin θ_(CF) =n _(w) sin θ_(w) , n _(w) sin θ_(w) =n _(air) sinθ_(air)  [Equation 1]

Equation 2 may be derived based on a relation of the interface betweenthe window 500 and external air in Equation 1.

$\begin{matrix}{n_{w} = {n_{air}\frac{\sin\;\theta_{air}}{\sin\;\theta_{w}}}} & \left\lbrack {{Equation}\mspace{14mu} 2} \right\rbrack\end{matrix}$

Also, Equation 3 may be derived based on the relation of the interfacebetween the color filter layer 420 and the window 500 in Equation 1 andEquation 2.

$\begin{matrix}{{n_{CF} = {{n_{w}\frac{\sin\;\theta_{w}}{\sin\;\theta_{CF}}} = {n_{air}\frac{\sin\;\theta_{air}}{\sin\;\theta_{CF}}}}},{\theta_{CF} = {\sin^{- 1}\left( {\frac{n_{air}}{n_{CF}}\sin\;\theta_{air}} \right)}}} & \left\lbrack {{Equation}\mspace{14mu} 3} \right\rbrack\end{matrix}$

Likewise, Equation 4 may be derived based on the relation of theinterface between the second inorganic encapsulating layer 330 and thecolor filter layer 420 in Equation 1 and Equation 3.

$\begin{matrix}{{n_{3} = {{n_{CF}\frac{\sin\;\theta_{CF}}{\sin\;\theta_{3}}} = {n_{air}\frac{\sin\;\theta_{air}}{\sin\;\theta_{3}}}}},{\theta_{4} = {\sin^{- 1}\left( {\frac{n_{air}}{n_{4}}\sin\;\theta_{air}} \right)}}} & \left\lbrack {{Equation}\mspace{14mu} 4} \right\rbrack\end{matrix}$

Also, Equation 5 may be derived based on the relation of the interfacebetween the first inorganic encapsulating layer 310 and the organicencapsulating layer 320 and the relation of the interface between theorganic encapsulating layer 320 and the second inorganic encapsulatinglayer 330 in Equation 1 and Equation 4 (wherein i is 1 or 2).

$\begin{matrix}{{n_{i} = {{n_{i + 1}\frac{\sin\;\theta_{i + 1}}{\sin\;\theta_{i}}} = {n_{air}\frac{\sin\;\theta_{air}}{\sin\;\theta_{i}}}}},{\theta_{i} = {\sin^{- 1}\left( {\frac{n_{air}}{n_{i}}\sin\;\theta_{air}} \right)}}} & \left\lbrack {{Equation}\mspace{14mu} 5} \right\rbrack\end{matrix}$

A distance traveled by light in the first inorganic encapsulating layer310 in a direction (+x direction) perpendicular to a direction (+zdirection) perpendicular to the pixel electrode 210 is indicated by Δx₁;a distance traveled by light in the organic encapsulating layer 320 inthe direction (+x direction) perpendicular to the forward direction (+zdirection) is indicated by Δx₂; a distance traveled by light in thesecond inorganic encapsulating layer 330 in the direction (+x direction)perpendicular to the forward direction (+z direction) is indicated byΔx₃; and a distance traveled by light in the forward direction (+zdirection) in the color filter layer 420 by a thickness of thelight-shielding layer 410 in the direction (+x direction) perpendicularto the forward direction (+z direction) is indicated by Δx_(BM). Then, atotal distance Δx traveled by light in a direction perpendicular to theforward direction (+z direction) is as defined below in Equation 6.

$\begin{matrix}{{\Delta\; x} = {{{\sum\limits_{i = 1}^{3}{\Delta\; x_{i}}} + {\Delta\; x_{BM}}} = {{\sum\limits_{i = 1}^{3}{d_{i}\tan\;\theta_{i}}} + {d_{BM}\tan\;\theta_{CF}}}}} & \left\lbrack {{Equation}\mspace{14mu} 6} \right\rbrack\end{matrix}$

Equation 7 is derived by substituting Equations 3 to 5 into Equation 6.

$\begin{matrix}{{\Delta\; x} = {{\sum\limits_{i = 1}^{3}{d_{i}\tan\left( {\sin^{- 1}\left( {\frac{n_{air}}{n_{i}}\sin\;\theta_{air}} \right)} \right)}} + {d_{BM}{\tan\left( {\sin^{- 1}\left( {\frac{n_{air}}{n_{CF}}\sin\;\theta_{air}} \right)} \right)}}}} & \left\lbrack {{Equation}\mspace{14mu} 7} \right\rbrack\end{matrix}$

Heretofore, an example in which three layers are provided between theopposite electrode 230 and the color filter layer 420 has beendescribed. In embodiments, a plurality of upper layers may be providedon the opposite electrode 230 and the color filter layer 420 may beabove the upper layers. In this case, Equation 7 may be modified asbelow in Equation 8 (wherein the number of the plurality of upper layersis represented by m which is a natural number of at least 1).

$\begin{matrix}{{\Delta\; x} = {{\sum\limits_{i = 1}^{m}{d_{i}{\tan\left( {\sin^{- 1}\left( {\frac{n_{air}}{n_{i}}\sin\;\theta_{air}} \right)} \right)}}} + {d_{BM}{\tan\left( {\sin^{- 1}\left( {\frac{n_{air}}{n_{CF}}\sin\;\theta_{air}} \right)} \right)}}}} & \left\lbrack {{Equation}\mspace{14mu} 8} \right\rbrack\end{matrix}$

In this case, suppose that ‘L’ represents a distance between an edge ofthe emission area of the light emission layer 220 in the direction (+xdirection) which faces the light-shielding layer 410 and an edge of thelight-shielding layer 410 in a direction (−x direction) which faces thelight emission layer 220. Then, the organic light-emitting displayapparatus according to the present embodiment satisfies the followingInequality 9.

$\begin{matrix}{L \geq {{\sum\limits_{i = 1}^{m}{d_{i}{\tan\left( {\sin^{- 1}\left( {\frac{n_{air}}{n_{i}}\sin\;\theta_{air}} \right)} \right)}}} + {d_{BM}{\tan\left( {\sin^{- 1}\left( {\frac{n_{air}}{n_{CF}}\sin\;\theta_{air}} \right)} \right)}}}} & \left\lbrack {{Inequality}\mspace{14mu} 9} \right\rbrack\end{matrix}$

When L does not satisfy Inequality 9, this indicates that at least someof the light generated at the edge of the emission area of the lightemission layer 220 in the direction (+x direction) toward thelight-shielding layer 410 is blocked by the light-shielding layer 410and not emitted externally, thereby decreasing light efficiency.

However, L may satisfy Inequality 9 in the organic light-emittingdisplay apparatus according to the present embodiment, and thus,extraction efficiency of light generated by the emission area of thelight emission layer 220 may substantially increase. In this case, theemission area of the light emission layer 220 may correspond to an areaof the pixel electrode 210, which is not covered by the pixel-defininglayer 180. Also, the edge of the emission area of the light emissionlayer 220 in the direction (+x direction) toward the light-shieldinglayer 410 may be regarded as a portion of the light emission layer 220,which corresponds to a boundary of the area of the pixel electrode 210,which is not covered by the pixel-defining layer 180.

According to the above description, the encapsulation layer 300 includesthree layers, i.e., the first inorganic encapsulating layer 310, theorganic encapsulating layer 320, and the second inorganic encapsulatinglayer 330. In embodiments, the plurality of upper layers include thefirst inorganic encapsulating layer 310, the organic encapsulating layer320 on the first inorganic encapsulating layer 310, and the secondinorganic encapsulating layer 330 on the organic encapsulating layer320. However, the embodiments are not limited thereto. For example, theplurality of upper layers may include a plurality of inorganicencapsulating layers and a plurality of organic encapsulating layerswhich are alternatively stacked on one another. Each of the inorganicencapsulating layers may include at least one selected from siliconoxide, silicon nitride, and silicon oxynitride, and each of the organicencapsulating layers may include at least one selected frompolyacrylate, PET, PEN, polycarbonate, polyimide, polyethylenesulfonate, polyoxymethylene, and polyarylate.

From among the plurality of upper layers described in relation toInequality 9, the lowermost layer in the direction (−z direction) facingthe light emission layer 220 may directly contact the opposite electrode230. In embodiments, other layers such as a capping layer or a filmlayer may be provided between the opposite electrode 230 and theencapsulation layer 300. In this case, the plurality of upper layers maybe regarded as including the encapsulation layer 300 and other layers,e.g., a capping layer or a film layer. Also, when other layers arebetween the encapsulation layer 300 and the color filter layer 420, theother layers are also included in the plurality of upper layersdescribed above in relation to Inequality 9.

With regard to Inequality 9, ‘L’ is a function of respective thicknessesand refraction indices of the plurality of upper layers, a thickness ofthe light-shielding layer 410, a refraction index of the color filterlayer 420, a refraction index of air, and a final refraction angle. Inembodiments, whether other layers, such as a touch screen layer, areprovided between the color filter layer 420 and the window 500 andwhether an air layer is provided between the color filter layer 420 andthe window 500 do not affect ‘L.’ Therefore, even when other layers,such as a touch screen layer, or the air layer is provided between thecolor filter layer 420 and the window 500, as long as Inequality 9 issatisfied, the organic light-emitting display apparatus is within thescope of the present inventive concept.

When ‘θ_(air)’ is 90°, the organic light-emitting display apparatus hasa very wide viewing angle. In this case, Inequality 9 may be modified asbelow in Inequality 10.

$\begin{matrix}{L \geq {{\sum\limits_{i = 1}^{m}{d_{i}\tan\left( {\sin^{- 1}\left( \frac{n_{air}}{n_{i}} \right)} \right)}} + {d_{BM}{\tan\left( {\sin^{- 1}\left( \frac{n_{air}}{n_{CF}} \right)} \right)}}}} & \left\lbrack {{Inequality}\mspace{14mu} 10} \right\rbrack\end{matrix}$

Also, when the refraction index of air is equal to 1, Inequality 10 maybe modified as below in Inequality 11.

$\begin{matrix}{L \geq {{\sum\limits_{i = 1}^{m}{d_{i}{\tan\left( {\sin^{- 1}\left( \frac{1}{n_{i}} \right)} \right)}}} + {d_{BM}{\tan\left( {\sin^{- 1}\left( \frac{1}{n_{CF}} \right)} \right)}}}} & \left\lbrack {{Inequality}\mspace{14mu} 11} \right\rbrack\end{matrix}$

For example, supposing that, in the structure as shown in FIG. 2, thefirst and second inorganic encapsulating layers 310 and 330 includesilicon oxide and each have a refraction index of 1.46 with respect to550 nm wavelength light, the organic encapsulating layer 320 includesPET and has a refraction index of 1.65 with respect to 550 nm wavelengthlight, and the color filter layer 420 includes aluminum oxide and has arefraction index of 1.7 with respect to 550 nm wavelength light. Then, Lmay be as defined below in Inequality 12, wherein d₁ represents athickness of the first inorganic encapsulating layer 310, d₂ representsa thickness of the organic encapsulating layer 320, and d₃ represents athickness of the second inorganic encapsulating layer 330.L≥0.94d ₁+0.76d ₂+0.94d ₃+0.73d _(BM)  [Inequality 12]

Therefore, when d₁ is 1.5 μm, d₂ is 2.5 μm, d₃ is 1 μm, and d_(BM) is 2μm, L has to be about 5.71 μm to prevent a decrease in light extractionefficiency.

An inorganic encapsulating layer and an organic encapsulating layer mayhave different refraction indices according to wavelengths. FIG. 3 is agraph of a refraction index according to wavelengths of silicon oxide,and FIG. 4 is a graph of a refraction index according to wavelengths ofsilicon nitride. As shown in FIGS. 3 and 4, the refraction index of theinorganic encapsulating layer may vary according to wavelengths. FIG. 5is a graph of a refraction index according to wavelengths ofpolyacrylate, and FIG. 6 is a graph of a refraction index according towavelengths of PET. As shown in FIGS. 5 and 6, the refraction index ofthe organic encapsulating layer may vary according to wavelengths. Thisalso applies to color filter layers.

Therefore, when an organic light-emitting display apparatus includes ared sub-pixel, a blue sub-pixel, and a green sub-pixel, a minimum valueof L that satisfies Inequality 9 may vary in each of the sub-pixels.Referring to FIGS. 3 to 6, in the case of silicon oxide, siliconnitride, polyacrylate, and PET, the refraction index may decrease as thewavelength increases. Based on the wavelength dependence of therefraction index in Inequality 9 or 11, the minimum value of L increasesas the wavelength increases. Therefore, the green sub-pixel has agreater minimum value of L than the blue sub-pixel, and the redsub-pixel has a greater minimum value of L than the green sub-pixel. Inembodiments, however, the distance L may be limited to an amount suchthat a portion of light-shielding layer 410 may be sufficiently formedbetween two immediately neighboring sub-pixels, although the inventionis not limited thereto.

By generalizing above embodiments, an organic light-emitting displayapparatus according to the following embodiment is also within the scopeof the present inventive concept.

In embodiments, as shown in FIG. 7, the organic light-emitting displayapparatus according to the present embodiment includes an array ofpixels, each of which includes first to third sub-pixels 200 a, 200 band 200 c, an encapsulating layer 330 on the first to third sub-pixels200 a-200 c, a light-shielding layer 410 on the encapsulating layer 330and corresponding to areas between the first to third sub-pixels 200a-200 c, and a color filter layer 420 on the encapsulating layer 330.The first sub-pixel 200 a includes a first light emission layer 220 aemitting first light having wavelength belonging to a first wavelengthband, the second sub-pixel 200 b includes a second light emission layer220 b emitting second light having wavelength belonging to a secondwavelength band, and the third sub-pixel 200 c includes a third lightemission layer 220 c emitting third light having wavelength belonging toa third wavelength band. Here, the wavelength of the second light islonger than wavelength of light belonging to the first wavelength band,and the wavelength of the third light is longer than wavelength of lightbelonging to the second wavelength band. For example, the firstwavelength band may be 400-500 nm, the second wavelength band may be500-600 nm, and the third wavelength band may be 600-1000 nm. FIG. 7shows L1 that represents a distance between an edge Ee1 of an emissionarea of the first light emission layer 220 a and a first edge Es1 of thelight-shielding layer 410 which defines a first hole of thelight-shielding layer 410 and surrounds the emission area of the firstlight emission layer 220 a when viewed along z-axis which may extend ina thickness direction of the apparatus (or when viewed in a viewingdirection perpendicular to a major surface of the substrate 100). FIG. 7also shows L2 that represents a distance between an edge Ee2 of anemission area of the second light emission layer 220 b and a second edgeEs2 of the light-shielding layer 410 which defines a second hole of thelight-shielding layer 410 and surrounds the emission area of the secondlight emission layer 220 b when viewed along z-axis (or when viewed inthe viewing direction perpendicular to the major surface of thesubstrate 100). FIG. 7 further shows L3 that represents a distancebetween an edge Ee3 of an emission area of the third light emissionlayer 220 c and a third edge Es3 of the light-shielding layer 410 whichdefines a third hole of the light-shielding layer 410 and surrounds theemission area of the third light emission layer 220 c when viewed alongz-axis (or when viewed in the viewing direction perpendicular to themajor surface of the substrate 100). Then, as described above, based onthe wavelength dependence of the refraction index in Inequality 9 or 11,L1<L2<L3 (see FIG. 7). Thus, extraction efficiency of light generated byeach of the first to third light emission layers 220 a-220 c may besubstantially increased.

While one or more embodiments have been described with reference to thefigures, it will be understood by those of ordinary skill in the artthat various changes in form and details may be made therein withoutdeparting from the spirit and scope as defined by the following claims.

What is claimed is:
 1. An organic light-emitting display apparatuscomprising: an array of pixels disposed over a substrate, each pixelcomprising: a first sub-pixel comprising a first light emission layerconfigured to emit first light having a first wavelength within a firstwavelength range; a second sub-pixel comprising a second light emissionlayer configured to emit second light having a second wavelength withina second wavelength range, the second wavelength of the second lightbeing longer than a wavelength of light within the first wavelengthrange; and a third sub-pixel comprising a third light emission layerconfigured to emit third light having a third wavelength within a thirdwavelength range, the third wavelength of the third light being longerthan a wavelength of light within the second wavelength range; anencapsulating layer disposed over the first to third sub-pixels; alight-shielding layer disposed over the encapsulating layer; and a colorfilter layer disposed on the encapsulating layer, wherein L1<L2<L3 issatisfied when L1 represents a distance between an edge of an emissionarea of the first light emission layer and a first edge of thelight-shielding layer when viewed in a viewing direction perpendicularto a major surface of the substrate, L2 represents a distance between anedge of an emission area of the second light emission layer and a secondedge of the light-shielding layer when viewed in the viewing directionperpendicular to the major surface of the substrate, and L3 represents adistance between an edge of an emission area of the third light emissionlayer and a third edge of the light-shielding layer when viewed in theviewing direction perpendicular to the major surface of the substrate.2. The organic light-emitting display apparatus of claim 1, wherein thefirst edge of the light-shielding layer defines an opening through whichlight emitted from the first light emission layer travels, and whereinthe distance L1 is determined such that substantially the entire amountof the light emitted from the first light emission layer toward theencapsulation layer travels through the opening.
 3. The organiclight-emitting display apparatus of claim 1, wherein the first edgeforms a first closed loop surrounding the emission area of the firstlight emission layer, wherein the second edge forms a second closed loopsurrounding the emission area of the second light emission layer, andwherein the third edge forms a third closed loop surrounding theemission area of the third light emission layer.